This paper presents the results of laboratory tests measuring typical gel system effectiveness in conformance control. The evaluated gel systems are a metal-complexed polymer system, an organic crosslinked-polymer system, and an in-situ polymerized system. All the systems are typical, commercially available systems used for water control in sandstone formations. The effects of temperature, differential pressure vs. permeability, and adsorption are investigated and quantified.The first set of core-flood experiments was performed with 1-ft long, 2-in. diameter Brown sandstone cores. The test temperatures were 140° and 240°F. The second set of experiments was run in a composite system with two 6-in. long, 1-in. diameter parallel coreholders. One coreholder contained a Brown sandstone core and the other coreholder held a Berea sandstone core. The permeability of the Brown sandstone core was 5 to 10 times greater than that of the Berea sandstone.The parametric studies carried out with these gels showthe effect of differential pressure vs. permeabilitybehavior of the water-control systems during placementadsorption characteristicsthe effect of the gel systems on nontargeted intervals when placed without zonal isolationThe organic crosslinked-polymer system provided the highest gel-threshold pressure. The test results indicate an improved injectivity profile after an in-situ gelation treatment. The permeability of the untargeted intervals was also affected during nonselective treatments. A larger slug had a larger impact on nontargeted zones proportional to the zones' permeabilities. Therefore, zonal isolation is strongly recommended. Polymer adsorption on rock surfaces and sensitivity of the metal-based crosslinker to the chemical environment can reduce gel-system effectiveness.